First off: thank you, thank you, thank you.
It’s all about the counting. Every 8-bar phrase (=32 beats) something new starts. So as long as you “obey” that the first downbeats of the phrases line up, you are in the clear. Personally I think for a lot of music an 8-beat transition is on the short side. More natural would be a 4-bar or even 8-bar bit (16 or 32 beats).
Knowing your music intimately helps a lot in determining what a good point is to mix out and what to mix in. If the beatmatch is tight, EQ-ing the lows or using filters make for easy and clean transitions that can run as long as you want.
Another tip is to make a loop (length depending on what it sounds like, trust your ears) instead of a cue point. Then when the track goes into the loop you have plenty of time to do a nice transition.
Try to be flexible here. Sometimes I have a track that has vocals til the end. I’ll choose not to beatmatch but use a cut or drop. Sometime I have tracks that have a 64-beat outro and I’ll run a 32 bit transition. Sometimes (if a track has a really recognisable beginning) I’ll just stutterplay that beginning on the beats a few times and then on the downbeat play the new track and cut the old one (people already recognised the incoming track and are ready and waiting.
There is truly a zillion ways to do this. So don’t be to rigid about having all your tracks with an 8-beat hook.